<?php
/**
 * Created by PhpStorm.
 * User: 氓羽
 * Date: 2018-4-13
 * Time: 14:25
 */

class Test{
    private $abc = 'abc';

    public function __isset($var)
    {
        return isset($this->$var) ? true : false;
    }

}
$test = new Test();
/*var_dump(isset($smarty_test->abc));*/